OSCE — Porokeratosis

Brief (to candidate)

You will assess a patient with a presentation consistent with Porokeratosis.
You have 8 minutes to take a focused history, outline examination, investigations, and management including red flags.

Clinical context

Porokeratosis is a clonal disorder of epidermal keratinisation, defined histologically by the PATHOGNOMONIC CORONOID LAMELLA — a vertical column of parakeratotic cells overlying a diminished granular layer with underlying dyskeratotic keratinocytes. Five classical variants are recognised: classic porokeratosis of Mibelli (large plaque, childhood onset), disseminated superficial actinic porokeratosis (DSAP, most common, sun-exposed adult skin, autosomal dominant with MVK/SLC17A9 mutations), linear porokeratosis along Blaschko's lines (highest malignant potential), porokeratosis palmaris et plantaris disseminata (palms/soles first), and punctate porokeratosis (1–2 mm keratotic spines on palms/

Candidate tasks

1. Clarify onset, severity, associated features, and red-flag symptoms.
2. State focused examination priorities.
3. List first-line investigations and any named score/criteria.
4. Give immediate resuscitation steps.
5. Outline definitive management with doses/routes where standard.
6. Name complications and disposition (ward / HDU / theatre / discharge safety-net).
7. Mention one special-population modifier (pregnancy, child, elderly, CKD).
8. Give immediate resuscitation steps.
9. Outline definitive management with doses/routes where standard.
10. Name complications and disposition (ward / HDU / theatre / discharge safety-net).
11. Mention one special-population modifier (pregnancy, child, elderly, CKD).

Examiner checklist

Model outline

Lead with the working diagnosis and life threats. Resuscitate before definitive tests when unstable. Use guideline-standard therapy with named agents and doses. Document escalation criteria and follow-up. A safe candidate is specific, structured, and never delays critical care for non-urgent imaging.^[1]